High-frequency tube structure



FIG.I

W. W. HANSEN HIGH-FREQUENCY TUBE STRUCTURE P-ll March 2l, 1950 Filed July 21, 1942 x 'm w March 21, 195o W W,HANSEN 2,500,944

HIGH-FREQUENCY TUBE STRUCTURE Filed Jul'y 2l, 1942 2 Sheets-Sheet 2 INVENTOR W. W. HAN SEN ATTORNEY yPatented Mar. 2l, Q

HIGH-FREQUENCY TUBE STRUTUR William W. Hansen, Garden City, N. Y., assignor to rElie Sperry Corporation, a corporation of Belaware Application July 21, 1942, Serial No. 451,796

19 Claims.

This invention relates, generally, to ultra high frequency electron beam velocity modulating Vacuum tube devices, and, more specifically, to a novel type of high frequency device useful as a push-pull amplifier or oscillator. In general, the operation of electron beam velocity modulating devices with attached resonators has been dcscribed in prior Patents No. 2,242,249, issued May 20, 1941, in the names of Sigurd F. Varian and William W. Hansen for Electrical converter and No. 2,242,275, issued May 20, 1941, in the name of Russell H. Varian for Electrical translating system and method.

The present invention discloses electron beam velocity modulating tube structures using two or a plurality of electron beams passing through two or a plurality of reentrant grid supporting structures in the associated pair of resonators. When a two beam device of this type is operated in push-pull, the device has the advantage of aifording twice as much grid area for the beam current as does a conventional single beam velocity modulation tube. The catcher resonator is given an impulse twice every cycle, instead of once a cycle as in a single beam tube, so that .if

more extreme loading of the catcher resonator can be allowed; or, for a given loading of the catcher, a resonator oi only about a half of the Q of the catcher resonator used in a single beam electron beam velocity modulating tube is needed. Also, all even harmonics in the catcher Voltage are eliminated. The device may be operated push-push if desired, but this has only the advantage of affording twice as much grid area. In

general, the greater the number of electron beams used, the greater is the elimination of harmonics in the catcher voltage.

It is therefore the principal object of the present invention to provide an ultra high frequency electron beam device utilizing a plurality of electron beams.

Another object is to provide a push-pull amplier, oscillator, or frequency multiplier velocity modulating tube of greater power output and freedom from harmonic distortion in the output.

A further object of the present invention is to provide improved ultra high frequency apparatus utilizing hollow cavity resonators and having a plurality of electron beams interacting therewith.

Still another object ci the present invention is to provide electron beam velocity modulation apparatus useful as ampliers, oscillators, or frequency multipliers, and having a plurality of velocity-modulated electron beams interacting with one or more cavity resonators having a corresponding plurality of electron permeable energyinterchanging gaps.

Other objects and advantages will become apparent from the specification, taken in connection with the accompanying drawings wherein the invention is embodied in concrete form.

In the drawings,

Fig. 1 is an elevation cross-section view of a generic form of the present invention.

Fig. 2 is a cross-section view of the paired resonators 3, 3 of Fig. l taken along the line 2 2 of that gure.

Fig. 3 is a cross-section view of a device similar to Fig. 1 having three reentrant portionsiin each resonator and using three electron beams.

Fig. 4 is similar to Fig. 3, but has four reentrant portions in each resonator, and uses four electron beams.

Figs. 5 to 11 are explanatory drawings showing the instantaneous relation of the magnetic elds to the electric elds in resonators of two, three, and four portions and utilizing two, three, and four electron beams, respectively.

Similar characters of reference are used in lall of the above figures to indicate corresponding parts.

Figs. 1 and 2 show a preferred form of the present invention using two electron beams and havingV reentrant portions in each of the two portions of each resonator 3, 3', 4, 4'. lThe resonators 3, 3', 4, 4' are similar in type to those shown in application Serial No. 420,770, filed November 28, 1941 in the names of William W. Hansen and Russell I-I. Varian, entitled Electric tuning control, issued April 13, 1948, as U. S. Patent No. 2,439,387. The configuration of the resonator portions 3, 3', 4, 4' constitutes electromagnetic eld phase control means. The discontinuities present in the side walls of the resonator portions 3, 3', 4, 4 are elective for providing the desired phase relationship among the voltages existing at the gaps defined by the respective grids 9, I0, 9', III', I2, I3, I2', I3'. Electrons emitted from hot cathodes I, I are accelerated by voltages impressed between the cathodes I, I' and entrance grids Ill, I0', and are projected through grids Ill, I Il'. In the spaces between grids I0 and 9, I0' and 9', the electrons are velocity modulated by an ultra high frequency electric eld existing between these grids. The distance from exit grids 9, 9 to catcher resonator entrance grids I2, I2', respectively, is made such that the velocity modulation of the beam has resulted in subsequent density modulation or grouping of the electrons by the time they reach the space between grids l2, i3 and i2', I3', respectively. Arrival of these bunches of electrons in the catcher grid interspaces results in maintaining electromagnetic oscillations in the associated resonator portions 4, 4 in the well known manner.

Concentric lines 5, and loops l, I may be used to introduce ultra high frequency energy into resonator portions 3, 3 under some circumstances, or loop may be used as a common means of excitation of both portions 3, 3 of the buncher resonator. Likewise, concentric lines 6, 5 and loops B, 8', or loop 25 may be used to excite the portions 4, 4 of the catcher resonator or to extract energy therefrom.

Any desirable modulation voltage may be applied to grids 2, 2 adjacent to cathodes i, i' to control or modulate the electron beam current therefrom. Tuning of the buncher resonator 3,

3' may be accomplished by movement of a conducting or dielectric cylinder Il', which is enclosed in a glass vacuum envelope I8, the movement being obtained by rotation of knob 23. The action of tuning cylinder i7 has been described in the last referred to application Serial No. 420,770 to be that of causing distortion of the electromagnetic field in the resonator 3, 3 in such a manner as to alter the resonant frequency of the resonator. Likewise, tuning of resonator 4, 4 may be effected by tuning cylinder I9 by rotation of knob 23, or by any other well known method.

As shown in Figs. 5 and 6l, there are two possible modes of oscillation of the two-portion resonators 3, 3 and ll, 4 shown in use in Fig. 1, In the case of the two-beam resonator as shown in Fig. 5, if the instantaneous polarities of the exit grids S, 9 of the resonator 3, 3 are opposite, the magnetic lines of force in the resonator appear instantaneously more or less concentric about the two poles 69, 69', run in opposing directions, and may be coupled with by a loop placed at 52. The loop at 52 is intended to be at right angles to the plane of the drawing, in the same position as the loop 25 of Fig. l. If the attached sides of the resonator 3, 3' are made smooth, such as is shown at 3" in Fig. 6, the type of mode shown in Fig. 6 can be more readily excited. Here, the exit grids 9, 9 always have instantaneously the same polarity. In this case, the lines of magnetic force travel around both poles in the manner shown and may be coupled with by a loop such as 53. The plane of loop 53 is intended to be at right angles to the plane of the drawing. It may be also placed in the position of loops l, 1 of Fig. l. The mode shown in Fig. 6 may also be excited in a resonator shape like that shown in Fig. 5. In general, these two modes will have different resonant frequencies for a given set of resonator dimensions, so that the resonator sizes will be dierent for a given frequency. These same considerations also apply to resonators 4 and 4.

Referring again to Fig. 1, if resonators 3, 3 and 4' are made to operate in the mode shown in Fig. 5, a push-pull device results which operates as an amplifier, energy being introduced by loop 25 and extracted after amplification from loop 26. If resonator li, d' is dimensioned to resonate at a harmonic of the resonant frequency of resonator 3, 3' a push-pull frequency multiplier results, whose operation is similar to that of the electron beam velocity modulating devices described in copending application Serial is, be equal.

No. 416,170, entitled High frequency tube structure, filed October 23, i941, patented Aug. 19, 1947 under Patent Number 2,425,738. Again, if resonators 3, 3 and 4, 4 are made to operate on the mode of Fig. 5 and at substantially the same frequency, and if loops 'l and 3 and 'l' and 8 are connected together by concentric line means, a push-pull oscillator results. Energy may best be removed from the concentric line attached to loop 26.

In the device shown in Fig. 1, when it is used as a push-pull amplifier, the large area of the opening between the two portions of each of the resonators affords the necessary high coupling between the two portions of that resonator. Separate single beam electron beam velocity modulating amplifiers may be used in push-pull, but two such separate amplifiers would require very accurate adjustment of frequency and power output to keep them operating in push-pull. Also, in the two-beam device, harmonic distortion of the output frequency is avoided, especially in case of high power input and extreme output loading.

The device may be also operated in push-push connection, if desired, by operating the catcher resonator in the mode shown in Fig, 6, in which case the velectron beam voltages or the beam drift tube transit times or both are adjusted to cause both beams to give up energy to the catcher resonator..

Polyphase devices similar to that shown in Fig. 1 may be made using three, four, or a larger plurality of electron beams traversing a pair of resonators in which three, four, or a corresponding plurality of reentrant grid-mounting poles exist. In Fig. 3 is shown the cross-section of a resonator with three portions 2l, 28, and 29, in each of which is centrally positioned a reentrant tube mounting grid structures 30, 3i, 32, respectively, through which respective electron beams are projected. Tuning may again be accomplished by a centrally positioned axially movable conducting cylinder, as at 33, the metal slug being placed so that the poles |30, 435, i32 of the resonator are placed symmetrically about it. Concentric lines attached to loops 34, 35, 36, placed in planes at right angles to the plane of the drawing, may be placed in each of the resonator portions 2l, 2S, 29, respectively, as needed.

In a resonator of this shape, three modes of oscillation are possible. In one mode, as shown in Fig. '7, all of the exit grids of the resonator have the same instantaneous polarity. In this case the lines of magnetic force are more or less concentric to the poles l30, l3l, 132, and all run in the same sense at any given instant. This mode may be coupled t0 by a loop 54 placed at right angles to the plane of the drawing, as shown in Fig. 7, or by either of two similar loops placed at from the loop 54.

Another type of mode possible in a three pole resonator is shown in Fig. 8, this mode being essentially a three-phase excitation. A certain instantaneous picture of the electromagnetic field for this mode shows one pole positive and increasing, one negative and decreasing, and one at zero potential. After lapse of one-third of the period of the operating frequency, the conditions of these particular poles will rotate through a 120, etc. As the sense of rotation may be in either direction, there are actually two possible frequencies due to this mode, although they may lie exactly on top of each other, that Either of these modes may be excited by means of a loop at right angles to the plane of the drawings as shown at 56. It is also evident that there are two other symmetrically located and equivalent possible positions for this loop.

It is seen that a three beam polyphase device of the type shown in Fig. 1 may be made by using two resonators of the construction of Fig. 3 having modes shown in Fig. 8 substituted for the resonators of Fig. l, or that similar polyphase devices may be made by using two such resonators having modes of the type shown in Fig. 7.

Polyphase devices may be made by using four electron beams passing through four reentrant poles containing grids such as exit grids 42, 43, 44, 45 in resonator portions 37, 38, 39, and 4I, respectively, as shown in Fig. 4 in cross-section. Tuning may again be accomplished by means of metal or dielectric slug 4B, and ultra high frequency energy may be coupled into or out of the resonator portions by means of loops 41, 48, 49

and 5|.

In the case of the four pole resonator, there are four possible types of excitation. Fig. 9 shows a mode in which the polarity of all of the poles is instantaneously the same, the lines of magnetic force being more or less concentric circles around the poles, all directed in the same sense. This inode may be coupled to by means of a loop as at 9| or by any of three other loops g placed in analogous symmetrical positions.

Fig. 10 illustrates another mode of excitation of such four pole resonators in which an instantaneous picture shows two of the poles of one polarity and two of the poles of the opposite polarity. Such a mode may be excited, for example, by a loop placed at 59. A third mode, whose frequency may be exactly the same as that of the resonator of Fig. 10, is produced by rotation of the fields and the loop 59 through 90 in resonator 58. The fourth mode of excitation is shown in Fig. 11 in which the diagonally opposite poles 42 and 45 are of one polarity and diagonally opposite poles 43 and 44 are of the opposite polarity at any given instant. This mode may be coupled to by a loop placed at 51 or at any one of three other analogous and symmetrically located positions. It is seen that the exact form of the lresonator may aid in determining the type of excitation of the resonator, as is shown in each of these groups of illustrations depicting modes 'of oscillation of the two, three, and four pole resonator. It is also seen that, if desired, any of these modes may be set up by use of external coupling loops such as 'l and 'I' of Fig. 2; 34, 35, 36 in Fig. 3, etc., if these loops are excited in the proper phase relative to one another, by means of concentric lines or by use of wave guides.

Push-pull devices similar to that of Fig. 1 may be made by the use of two resonators having modes of oscillation similar to that shown in Fig. 10 or two similar to that shown in Fig. 11, Pushpush devices may be made using two resonators oscillating in the mode shown in Fig. 9.

In accordance with the provision of the patentl statutes, there is described herein the principal operation of the invention, together with the apparatus which is now considered to represent the best embodiment thereof. It is to be understood, however, that the apparatus shown is only illustrative and that the invention can be carried out by other means. Also, while it is designed to use the various features and elements in the combination and relations described, some of these may be altered and others omitted without interto interact with a respective electron beam after passage thereof through the corresponding reentrant portion and grids of said buncher resonator, means defining a field-free space surrounding the path of each of said beams between said resonators, means coupled to said buncher resonator for exciting said buncher resonator with a high frequency eld, and means coupled to said catcher resonator to abstract energy therefrom.

2. High-frequency electron-discharge apparatus comprising means for producing a plurality of parallel electron beams, means along the paths of said beams for velocity-modulating each of said beams cophasally in response to the same high frequency wave, an output resonator along the paths of all of said beams tuned to said wave and having a plurality of separate gaps respectively corresponding to each of said beams, said output resonator having substantially symmetrically disposed discontinuities in the side wall thereof for producing a mode of oscillation with progressively different phases of voltage at said gaps.

3. Apparatus as in claim 2 wherein said resonator has an output coupling loop located symmetrically with respect to said gaps.

4. High frequency electron discharge apparatus comprising means for producing a plurality of electron beams, means along the paths of said beams for simultaneously and periodically varying the velocities of the electrons of each of said beams at the same frequency and at the same phase, said last named means including means dening a lrst electromagnetic eld region having a like plurality of electron traversal spacesI registering with said beam paths, means defining a iield-free drift space surrounding the path of each of said electron beams for causing said velocity-varied electrons to become density-modulated, means along the path of said beams and beyond said drift spaces defining a second electromagnetic region having a like plurality of further electron traversal spaces registering with said -beam paths, and means providing predetermined phase displacement among the voltages resulting across said further traversal spaces of said second region due to the passage of' one of said beams thro-ugh said second region.

5. High frequency electron discharge apparatus as in claim 4, in which said predetermined phase displacements are relatively equally spaced.

6, High frequency electron discharge apparatus comprising a first cavity resonator means having a plurality of reentrant portions each defining an electron-permeable gap, a second cavity resonator 'means spaced from said first resonator and also having a plurality of reentrant portions each defining an electron permeable gap, means adjacent one of said cavity resonators for produc, ing a plurality of electron beams and for projecting each of said beams successively through a 18. Apparatus as in claim 17 further comprising a coupling loop in one of said end walls locat ed symmetrically with respect to and substantially between said apertures in one of said end walls.

19. Apparatus as in claim 17 further including a coupling loop in said side wall and located in a plane symmetrically placed with respect to said walls.

WILLIAM W. HANSEN.

REFERENCES 'CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Name Date Varian May 20, 1941 Number Number Certcate of orrecton Patent No. 2,500,944 March 21, 1950 WILLIAM W. HANSEN It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

b Column 8, line 15, after the Word means insert at one end of the paths of said eams;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oice.

Signed and sealed this 27th day of June, A. D. 1950.

[SEAL] THOMAS F. MURPHY,

Assistant Uommz'ssz'oner of Patents. 

